There are no applications related hereto heretofore filed in this or any foreign country.
1. Field of Invention
Our invention relates generally to measuring and testing, and more particularly to a mechanized penetration type tester that is computer operated and serviced for such testing and processes for fruit testing allowed by the tester.
2. Background and Description of Prior Art
The determination of the ripeness and the maturational state of fruit has been a human desire probably as long as fruit has been used as a food product. Through the history of such determinations the process has devolved from subjective tastable, visual and manual inspection to mechanized and sophisticated somewhat objective procedures, but substantial problems still remain to be resolved to provide meaningful objectivity. The instant invention seeks to solve or alleviate various of these remaining problems, especially as they relate to softer fruits of the pippin and drupe types.
Visual inspection and manual manipulation were early found to be only rudimentary indicators of ripeness and not indicative to any substantial degree, if at all, of maturational state, both by reason of their substantial subjectivity and their lack of any substantial functional relationship to the characteristic sought to be determined. Both methods are still widely used, however, not only by unsophisticated consumers, but also by professionals.
In the early development of more objective fruit testing, the firmness of fruit, or more properly its resistance to pressure deformation or plunger penetration, were found to be more reliable indicators of ripeness and maturation state than visual appearance, manual manipulation and other similar subjective determiners. In modern fruit testing measures of firmness are more widely used as indicators of the fruit condition than are more subjective attributes. As the desire for increased accuracy of fruit testing grew, the testing processes passed from the partially subjective manually manipulable penetration processes to the greater objectivity of mechanically controlled testing devices, firstly of the manually operated type the and subsequently of the mechanically powered and controlled type, to increase accuracy, reliability and repeatability of the testing results. Mechanical testers have developed along the lines of both destructive or penetration type devices and nondestructive or impingement type devices, with representatives of each type of device being used in the modern day fruit testing arts.
Probably the most commonly used present day fruit tester, and that which often serves as the determiner of fruit quality for regulatory agencies, is a manually operated intrusion type tester that provides a cylindrical plunger which is inserted by direct manually applied force into the meat of a fruit to an often variable distance by an operator with measurement only of the maximum force required for insertion being determined and used as the indicator of fruit quality. Such testers provide quite variant results when determined by repeatability, are fairly unreliable in determining fruit ripeness and are substantially unreliable in determining the state of fruit maturation, which is indicative of the course of future development and especially of shelf life of the fruit. The modern trend in private, as opposed to regulatory, testing devices has been toward more sophisticated non-destructive impingement type devices that measure force required for impingement of an object into a fruit surface without skin rupture or the amount of impingement caused by a predetermined force applied on the surface of the fruit by an object or a pressurized gas stream.
The instant mechanism differs from this current and other known fruit testing apparatus by providing a computer controlled intrusive plunger that is mechanically forced into a fruit to a substantial predetermined depth at constant velocity, constant load or a combination of both for measurement in rapid sequence of the mechanical resistance to plunger penetration throughout the length of the plunger""s intrusive course. The mechanism provides an electrically powered motor that drives a ball-screw motion translator through a transmission mechanism. The motor has an attached encoder and associated control circuit that regulate the velocity and rotational direction of the motor and thereby the linear velocity and displacement of the plunger responsive to software generated computer commands. The plunger is supported through a load cell which measures the force applied to the plunger throughout its trajectories. The plunger displacement, velocity and applied force measurements are communicated to the associated computer by feedback circuits for recordation and analysis at approximately 30,000 sequential sampling points along a single plunger trajectory.
Prior testers that have provided intrusive plunger type testing of fruit or similar penetrable products generally have not provided for the accurate determination of force resisting plunger penetration at closely spaced and positionally determinable points along a predetermined plunger trajectory and are distinguished from the instant mechanism in this regard. Additionally prior devices are not known to have allowed the selective determination of resistive force of a fruit to plunger penetration at either constant velocity or constant load, to have provided sufficient accuracy in control and measure of plunger speed and position to provide consistently repeatable results and have not determined penetration resistance at such small increments as is allowed by the instant device.
The accuracy of control and measurement of the instant tester arises from the computer controlled and electronically sensed mechanical structure that provides a motor powering a speed reducing cog belt transmission that operates a ball screw motion translator to lineally move a plunger interconnected through an intervening strain gauge block having four strain gauges interconnected in an amplified bridge circuit for force measurement. This type of finely controllable and accurately determinable drive structure is not known to have been previously used for penetration type fruit testing purposes.
The development of such a precision tester has given new insight not only into existing fruit condition, but also into the state and theory of the fruit maturation process itself which has allowed development of new methods for determining ripeness, life stage, condition and future development as a function of time. The tester thusly provides both a scientific informational tool and a practical economic tool to aid determination of conduct for dealing with fruit, both before and after picking. It has been found by accurate and fine measurement at closely placed intervals along a fruit radius that resistance to plunger penetration varies considerably in different parts of a fruit and that this variance is more functionally related to the physiological state of the fruit, and especially to maturation, than is an average or maximum measure of resistivity to plunger penetration. This functional relationship and various of its patternations and their relationships to each other have been used to develop new and different measures of fruit maturation and to give new insight into the nature of that process to allow it to be more meaningfully and accurately used in dealing with fruit throughout the various developmental stages of its life span.
The peripheral zone of most fruits, and especially of apples, generally provides less resistance to plunger penetration than the radially medial or central core area in any state of fruit maturation, prescinding from the initial force required to penetrate the fruit skin.
With the finer analysis allowed by the instant tester it has been found that the physical characteristics commonly associated with fruit ripeness and quality vary considerably in different radial zones of the fruit at any given time, with characteristics commonly associated with ripeness and with subsequent deterioration occurring at different rates in different radial zones of the fruit, so measurement of firmness in the outer layer is a poor predictor of internal fruit condition. This finding has allowed measurements of characteristics in different radial zones of a fruit to both accurately determine the existing state of the fruit and also serve as an accurate means of predicting the change in the nature of the fruit at future times. This has allowed development of methods and processes for use with the tester that provide accurate prediction of ripeness, which heretofore often has been related to the balance of starch and sugar content, and of subsequent consumer desirability, which largely has been related to crispness or firmness of the fruit meat especially in the outer peripheral zone. The tester also allows accurate predictability of acceptable limits for these conditions and determination of the time when the limits will be attained to make the fruit unacceptable.
Processes have been developed and are presented for establishing numerical determination and determination of limits for fruit quality from combined measures of parameters derived from data developed through an entire fruit radius, especially to determine the desirability or quality of the fruit at the time of measurement. Comparative processes have also been developed and are presented to use the data within different radial zones of a fruit to not only provide accurate numerical indicators of quality, but also to relate the parameters in the different zones to each other to provide accurate indicators of the state of fruit maturation and a reliable method of predicting the future state of maturation of the fruit at future times. The measuration of parameters may be continuous through the entire fruit radius or more simply may be based on measures in three logically distinguishable zones of a fruit comprising and outer peripheral zone adjacent the fruit skin, a medial meat zone and the central core zone, or may be otherwise differentiated and refined to provide more detailed and accurate measures for particular types of fruit and particular conditions to be determined. These processes are distinguished essentially from maximal, minimal or gross averaging processes for determining fruit characteristics without regard to the area where the determined parameters are present. The analyses presented by our processes generally have not been possible with prior testing apparatus which did not provide sufficient reliability to allow repeatability of the tests to any substantial degree and have not heretofore been used in commercial or regulatory testing.
Our invention resides not in any one of these features individually, but rather in the synergistic combination of all of the structures of our tester which necessarily give rise to the functions flowing therefrom and the analysis processes essentially related thereto, as herein specified and claimed.
Our tester provides a plunger intrusion-type mechanism and an associated computer for control of the mechanism and for recordation, presentation and analysis of data sensed by the mechanism. An electrically powered variable speed motor carries an optical encoder to sense rotary direction and speed data, which is transmitted through feedback circuitry to the associated computer for analysis to determine control data to maintain preprogrammed motor function. Rotary motion is transmitted from the motor through a speed reducing cog-belt transmission to a ball screw motion translator that interconnects a strain block which in turn carries an intrusion plunger for linear motion. The strain block carries plural strain gauges interconnected by a bridge circuit to sense resistance to plunger penetration into a fruit and transmit that data to the associated computer. Preprogrammed computer software determines plunger position and resultant penetration into a fruit at either predetermined plunger speed or constant plunger resistive pressure in fine increments at least as small as one in 32,000 parts over the plunger trajectory and stores this data in computer memory.
Processes allowed by the fine measurement of parameters are set forth to determine and numerically represent the maturation state and present condition of fruit, generally of either pippin or drupe types, by analyzing the data through a radius of the fruit or in radial zones. Processes are also set forth for numerically determining and predicting the future maturation state of the fruit at future times by comparing the functional relationships of parameters within different radial zones.
In providing such a mechanism and associated processes it is:
A primary object to provide a plunger type intrusive tester that is serviced by a computer to allow measurement of plunger position at least 30,000 data points in a radial trajectory into a fruit and resistance to plunger penetration with a accuracy of at least 0.001 pound over a radial trajectory extending from the periphery to the center of the core area of a pippin or to the stone of a drupe.
Another primary object is to provide such an intrusive tester that has a mechanism controlled by computer output data determined from mechanism input data with all data transferred between the mechanism and computer through feedback type circuitry.
A further object is to provide such a tester that is of relatively small and portable nature and may be battery powered for field testing.
A further object is to provide mechanism for such a tester comprising a variable speed motor driving a cog-belt type speed reducing transmission that drives a ball-screw motion translator to move a plunger coupled through a strain gauge in a linear course to accurately measure plunger position, velocity and force resisting plunger motion, when coupled through electronic sensors and controllers with a controlling computer.
A further object is to provide such a tester that measures resistance to plunger penetration both at constant plunger velocity and at constant force resisting plunger penetration.
A still further object is to provide such apparatus and processes for measurement and determination of fruit condition that may simulate the results of present day manual impingement testing, but with substantially greater accuracy and repeatability.
A still further object is to provide such apparatus and processes that measure resistance to plunger penetration in predetermined radial zones of a fruit to allow comparison of the parameters in different zones to provide an accurate indicator of the present state and maturity of the fruit, methods for estimating fruit condition at future times, methods to estimate the time of ripeness of immature fruit for picking and the commercially acceptable life span of mature fruit.
A still further object is to provide such a tester that is of new and novel design, of rugged and durable nature, of simple and economic manufacture and one that provides accurate and repeatable test results with various fruits, vegetables or similar materials that are tested by plunger penetration and to provide essentially related processes for the determination of present condition, maturation state, future development and consumer desirability as allowed by reason of the fine, accurate and detailed data provided by the tester.